Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – With oxygen or halogen containing chemical bleach or oxidant...
Patent
1996-08-23
1999-05-11
Einsmann, Margaret
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
With oxygen or halogen containing chemical bleach or oxidant...
8111, 25218627, 25218628, 25218632, 25218643, C11D3/39
Patent
active
059027835
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to particles having a core of a peroxy compound and a coating comprising alkali metal silicate and a chelating agent. The invention also relates to preparation and use of the particles. Further, the invention relates to a composition containing such coated particles.
Powder detergent compositions often contain peroxy compounds as bleaching agents which release hydrogen peroxide or peroxy acids in aqueous solutions. However, many peroxy compounds are not storage stable. Their decomposition is supposed to be catalysed by metal cations moving comparatively freely through the water normally being present in detergents, but is also facilitated by the alkaline pH (normally from about 8 to about 12) and by other components commonly present in detergents, for example zeolites or bleaching activators such as TAED (tetraacetylethylene diamine), TAGU (tetraacetylglucoluril) or PAG (penta acetyl glucose).
In order to make environmental friendly detergents, it is desirable to use alkali metal carbonate peroxy hydrate, commonly known as percarbonate, as a bleaching agent. However, the activity of percarbonate in a detergent decreases rapidly through decomposition if the detergent is stored at normal room temperature and humidity.
Many attempts to stabilize percarbonate have been done, for example by mixing or coating with stabilizing substances such as borates, silicates or organic substances. Such stabilizing methods are described in the patent literature, for example in GB 1575792, EP 459625, U.S. Pat. No. 3975280 and EP 573731.
It has also been disclosed to combine percarbonate with chelating agents such as alkali metal citrate (see EP 546815) or phosphonic acids (see WO 91/15423).
CH 659082 describes a detergent additive comprising a mixture of a peroxide, an inorganic carbonate and an acid or its salt that is solid at room temperature.
U.S. Pat. No. 4075116 discloses a method of preparing sodium percarbonate from sodium carbonate and hydrogen peroxide, which method includes adding a compound selected from sodium sulfate, potassium sulfate, sodium pyrophosphate, potassium pyrophosphate, sodium metasilicate, sodium disilicate, sodium citrate, sodium glucoheptonate, sodium perborate, anhydrous sodium carbonate, potassium carbonate and mixed sodium and potassium carbonate. However, the patent is not addressed towards stabilization of previously prepared sodium percarbonate or to the inhibition of the other constituents of detergent mixtures containing percarbonate.
U.S. Pat. No. 4117087 discloses a method of preparing sodium percarbonate from sodium carbonate and hydrogen peroxide including addition of alkali metal silicate. Phosphonic acids, EDTA (ethylenediamine tetraacetic acid) or NTA (nitrilotriacetic acid) may be added to the hydrogen peroxide which is prepared for the precipitation of percarbonate.
The object of the present invention is to provide particles comprising a peroxy compound, particularly alkali metal percarbonate, with improved storage stability, particularly in detergent compositions. It is another object of the invention to provide particles comprising a peroxy compound only containing environmental friendly constituents.
Through the present invention, these objects has been fulfilled by providing particles having a core of a peroxy compound with capability of releasing hydrogen peroxide or peroxy acids in aqueous solutions, particularly in alkaline solutions. The particles have a coating containing alkali metal silicate and a chelating agent. Suitably, the coating contains an aliphatic organic compound as a chelating agent, the organic compound preferably comprising from 2 to 10 carbon atoms, most preferably from 4 to 8 carbon atoms. It is preferred to substantially exclude chelating agents containing phosphor such as phosphonic acid or salts thereof. It is also preferred to substantially exclude chelating agents which are not easily bio-degradable such as EDTA or DTPA (diethylene triamine pentaacetic acid, or chelating which for other reasons are questionable from an
REFERENCES:
patent: 3975280 (1976-08-01), Hachmann et al.
patent: 3977988 (1976-08-01), Tokiwa et al.
patent: 4075116 (1978-02-01), Mesaros
patent: 4117087 (1978-09-01), Dillenburg et al.
patent: 5340496 (1994-08-01), Sato et al.
Rompps Chemie--Lexikon, Upplaga 8, Band 2, 1981 p. 1503 "Glucosaure", 1981.
Kirk-Othmer Encyclopedia of Chemical Technology, Third Edition, vol. 5, p. 344.
Jigstam Monica
Lagnemo Hans
Einsmann Margaret
Eka Chemicals AB
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